Process of cleaning and burnishing metallic powders



Patented Aug. 21, 1928.

nairsn STATES) PATENT OFFICE.

JOHN A. DALY, on NEW ROCHELLE, new YORK.

PROCESS OF CLEANING AND BURNISI-IING METALLIC POWDERS.

No Drawing.

metallic surface with metal, to apply to said substance a metallicpowder, causing the same to adhere thereto either by embedding thepowder in a sticky substance applied to the substance to be coated, ormixing the metallic powder with some substance in the nature of alacquer or varnish, to render the coating conductive, and thereafterplacing the thus coated substance or article in an electrodepositingbath for electrodeposition.

Great difficulty has been experienced in these processes in securing aperfect and even strike of the electrodeposited metal. This diflicultyhas made it necessary to attach to the article or substance to be coateda number of attachments, and, in the case of large articles, aconsiderable number of such attachments has been necessary. Even aftersuch practice, it has been necessary to leave the substance to be coatedin the bath for c0nsiderable periods before a good strike could besecured, and in the case of some large articles it has been foundimpossible to secure a satisfactory electrodeposition.

In the former practice also it is found that the portions of thesubstance in which a successful strike was required become conductive inadvance of the remaining portions, thus developing a coating of uneventhickness, which is exceedingly objectionable.

By use of powder obtained according to the present method a perfectstrike may be secured over the whole of the article or substance in ashort space of time, and a coating of uniform thickness may be producedusing but a single attachment for electrical current to the substance orarticle to be coated.

It has been found that a particularly good strike can be secured byapplying a coating of powder of tin-lead alloy, which substancesApplication filed August 2, 1926. Serial No. 126,748.

are readily onidized if exposed to the air, and by the provision of thepresent invention these particles may have their surfaces effectivelycleaned of oxidation or other adhering particles, whereupon they may beused upon the electrodeposition process.

For the purpose of cleaning these particles 1 it has beendiscovered thatthey may be mi Xed with particles of a substance harder than themselvesand agitated while thus mingled 'whi chwill result in the effectivecleaning of the particles of the powder.

Operative substances as cleaning elements are found to be glass beads,preferably of small diameter, or small steel elements, and a desirableproportion of cleaning elements to powder is found to be four parts ofthe powder to one part of the cleaning elements.

\Vhile glass beads are found satisfactory for the purpose an objectionto their use is found in static electricity, which is produced by theagitation and with which the glass beads become charged upon theirsurfaces, thus causing the particles of the powder to adhere together orto the container. For this reason it is preferred to use the steelelements as a cleaningmedium.

The elements referred to with the powder mingled therewith may be.placed in any container and shaken by hand or machinery. It is desirableto utilize the ordinary tumbling barrel of the nature used by jewelersin cleaning small articles of jewelry.- After an agitation of from fiveto thirty minutes the powder will be found to have its par ticlesprovided with. bright surfaces, which may then be separated from thecleaning element and applied to the article to be electrically coated inthe manner above referred to.

Since a substantially instantaneous strike maybe produced upon theimmersion of the coatedarticle in the electroplating bath and because ofthe fine electrically conductive condition of theparticles a singleattachment for current to the article to be coated is sufficient toproduce an even electrodeposition over the whole of the article.

1. The process of burnishing metals in a state of line subdivision whichcomprises commingling the particles of metal with powder with separatedparticles of steel and agitating the mixture.

4:. The process of burnishing powdered lead tin alloy which comprisesmixing four parts of the powder with one part of small steel elementsand agitating the mixture.

JOHN A. DALY.

